- According to industry leader De Beers, the cut of a diamond is the most valuable trait. A diamond's cut includes both the facets and the proportions of the diamond's facets. It is not the actual shape of the diamond. The cut is what allows the diamond to catch the light. A diamond's cut should not be too shallow or too deep.
- Another criteria for diamonds is clarity. A flawless diamond will be free of any internal or external imperfections. Diamond imperfections can include clouding, scratches and internal crystallization. Most diamonds have a least slight imperfections, but a diamond that has obvious flaws will be less valuable.
- There are two considerations to make when looking at a diamond's color. Diamonds are graded on a color scale from "colorless" to "obvious color." A diamond that is colorless is very valuable. A diamond that has a great deal of color can also be very valuable, as this is a rare find. However, diamonds that fall in between these two categories are less valuable.
- Carat refers to the weight of the diamond. A carat is 0.2 g. If two diamonds have the exact same characteristics, but one is a larger carat, the larger diamond will be more valuable. It is rare to find a very large, flawless diamond. Therefore, these diamonds are much more valuable than smaller ones.
